Electrical and electronic elements in the field of power electronics are often understood to be semiconductor, elements, for example insulated gate bipolar transistors (IGBT's), thyristors, diodes, resistors, metal oxide semiconductor field effect transistors (MOSFETs), and combinations of components of this type and the like. The term “power electronics” is understood to include hereinunder power electronics elements that during operation can include a cutoff voltage of more than 500 volts. These electrical and electronic elements should be cooled during operation owing to the fact that as a result of the extremely high power densities they generate likewise extremely high thermal flows that should be efficiently transferred. In modern converters, these power electronics elements are often combined into groups in power modules. A converter can be used, for example, to drive an industrial mill, a vehicle, a ship and/or for the purpose of voltage conversion or converting voltage.
If the heat is not transferred from the semiconductor elements, said elements can become damaged and in the extreme case this can lead to an operator of the converter having to suffer interruptions in the operation as a result of repair work. Such interruptions in the operation should be avoided due to the fact that the interruptions can lead to considerable economic disadvantages for the operator of the converter.
Since the power density per structural volume of the converter increases with the ever-reducing size of converters, the specification for compact but nonetheless efficient cooling systems increases. Heat flows in power electronics can be transferred from a converter during operation of the converter by way of a cooling water flow that is connected to the converter or by way of a cooling air flow of a primary circuit by way of a heat exchanger. The heat flows of the power electronics elements are transferred to the primary cooling flow by means of a secondary cooling circuit by way of a heat exchanger.
Both when the primary cooling flow is in the form of a cooling water flow and also when the primary cooling flow is in the form of a cooling air flow, the magnitude of the heat energy that is to be thermally transferred from the secondary cooling circuit by way of the heat exchanger to the primary cooling flow can be significant because this magnitude influences the provision of installation space for the purpose of accommodating cooling channels of sufficient cross section, and also for accommodating pumps, fans and the like.